Conventional ways to make outlets in tubulars, commonly referred to as windows, involve setting a diverter, known as a whipstock, and properly supporting and orienting it. The whipstock can also be run attached to a bottom hole assembly that can include one or more mills and orientation equipment for the whipstock and even an anchor for the whipstock that can be set when the desired orientation is obtained for the whipstock. Milling windows incorporates possibilities that something could go different from plan. Mills can bore into the whipstock instead of being urged along its ramped surface until the casing wall is penetrated and an exit is made. Mills can become dull or make too early an exit that can result in the window being too short. The mills can become dull during the window forming procedure or the anchor for the whipstock can prematurely release. Typically windows made by the whipstock need to be very long because ramp angles on the whipstock are very small, in the order of about three degrees or less to avoid bogging down the widow mill with extreme lateral forces to get it to go through the wall. Windows are also made in stages with sequential mills that in series make the window wider than the previous mill. Using such systems of ever larger mills requires the system to withstand bending moments as progressively larger mills get onto the whipstock ramp and start widening the already started window. At times, the stress levels become excessive and connection failures are known to occur between mills.
Openings in tubulars are needed for other purposes such as normal production from the surrounding formation. Many times that is accomplished with perforating guns. The problems with perforating guns are the safety concerns of handling explosives and the potential for formation damage from shooting off the guns as well as other subsidiary issues of proper placement and support for the guns and retrieval after they are shot off.
While guns can be run in wireline for fast delivery to the desired location, assuming that the well is not too deviated, milling assemblies are run in on a tubular string that is either rotated from the surface or includes a downhole mud motor to rotate the mills.
The present invention takes a fresh approach to providing openings in tubulars that avoids many of the issues discussed above. In the preferred embodiment, an assembly is delivered on wireline for rapid deployment into the wellbore. The assembly comprises a processor which can selectively actuate a combination guiding and anchoring system that allows the assembly to be initially positioned in the desired spot and moved longitudinally to fashion any shape of opening or openings desired in a predetermined location or locations. One or more cutters can be extended for milling and the cutters can be moved in a predetermined arc while the assembly is moved uphole or downhole. Spare cutters are envisioned to allow a specific job to be finished without bit change or/and to allow the job to be completed faster. The rate of uphole or downhole movement can be controlled. The assembly can even make locating grooves for proper positioning of subsequent equipment after the desired opening or openings are made. These and other advantages of the present invention will be more apparent to those skilled in the art from a review of the drawings and description associated with the preferred embodiment while recognizing that the full scope of the invention is in the associated claims.